[PATCH net v2] net: airoha: Fix skb->priority underflow in

[Joe Damato]

On Mon, Jun 15, 2026 at 08:48:13PM +0800, Wayen Yan wrote:
> From b894fc031e307f1b6756ea9fcac98e82e23815e1 Mon Sep 17 00:00:00 2001
> From: "Wayen.Yan" <win847 at gmail.com>
> Date: Sun, 14 Jun 2026 07:30:54 +0800
> Subject: [PATCH net v2] net: airoha: Fix skb->priority underflow in
>  airoha_dev_select_queue()
> 
> In airoha_dev_select_queue(), the expression:
> 
>   queue = (skb->priority - 1) % AIROHA_NUM_QOS_QUEUES;
> 
> implicitly converts to unsigned arithmetic: when skb->priority is 0
> (the default for unclassified traffic), (0u - 1u) wraps to UINT_MAX,
> and UINT_MAX % 8 = 7, routing default best-effort packets to the
> highest-priority QoS queue. This causes QoS inversion where the
> majority of traffic on a PON gateway starves actual high-priority
> flows (VoIP, gaming, etc.).
> 
> Fix by guarding the subtraction: when priority is 0, map to queue 0
> (lowest priority), otherwise apply the original (priority - 1) % 8
> mapping.
> 
> Fixes: 2b288b81560b ("net: airoha: Introduce ndo_select_queue callback")
> Acked-by: Lorenzo Bianconi <lorenzo at kernel.org>
> Signed-off-by: Wayen <win847 at gmail.com>
> ---
>  drivers/net/ethernet/airoha/airoha_eth.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Hm, I tried to apply this patch to my tree just to see what would happen with
the duplicated SMTP headers and it looks like they just get added to the
commit message.

I think you might need to re-send it (but you'll have to wait 24 hours between
re-sends).

The code looks fine to me, though, so feel free to include my tag:

Reviewed-by: Joe Damato <joe at dama.to>